Smoke from a fire at the Abqaiq oil processing facility fills the skyline, in Buqyaq, Saudi Arabia. Picture: Al-Arabiya via AP, File

Attacks on two sites at the heart of Saudi Arabia's oil industry shut down more than 5% of global supply, sent oil prices as much as 20% higher and prompted the United States to blame Iran despite Tehran's denials.

* Yemen's Iran-aligned Houthi group, which is battling a Saudi-led coalition in Yemen, claimed responsibility for the attacks on Saturday on sites run by state-owned Saudi Aramco.

* U.S. Secretary of State Mike Pompeo ruled out Yemeni involvement and accused Iran of leading the attacks.

* U.S. President Donald Trump said the United States, which is embroiled in a row with Iran over its nuclear ambitions, was "locked and loaded" for a potential response.

* Russia said it was unacceptable to discuss possible retaliation and said that using the incident to increase tensions around Iran was counterproductive.

* An Iranian Revolutionary Guards commander said U.S. bases and aircraft carriers were within range of Iranian missiles, after Washington blamed Iran.

* Sunni Muslim Saudi Arabia has previously accused Shi'ite Muslim Iran, which lies across the Gulf, of carrying out attacks on its oil facilities, charges Tehran denies. Riyadh has not blamed any party for Saturday's strikes.

* Those attacks, which knocked out about 5.7 million barrels per day (bpd) of Saudi output, targeted sites in Abqaiq and Khurais, in eastern Saudi Arabia.

* Abqaiq processes crude from the giant Ghawar oil field for export to terminals in the Gulf and Red Sea.

* Oil prices soared as much as 20% on Monday, with Brent crude posting its biggest intra-day percentage gain since the Gulf War in 1991.

* Analysts said benchmark Brent, now trading at around $66 a barrel, could hit $100 if Riyadh failed to quickly bring back supply.

* The Organization of the Petroleum Exporting Countries is assessing the impact but says it is too early for members to take any action on raising production or holding a meeting, the UAE energy minister and other sources said.

* Saudi Aramco's full return to normal oil output volumes "may take months", two sources said on Monday.

* Saudi Arabia usually ships more than 7 million bpd of oil to global destinations and has for years served as the market's supplier of last resort.

* The attack, which knocked out more than half of Saudi Arabia's output, constrained its ability to use more than 2 million bpd of spare oil capacity held for emergencies.

* Saudi Aramco has been seeking to prepare for a share sale that would make it the world's largest listed company. 

Reuters